Method and device for assisting cardiovascular circulation



United States Patent [72] Inventor Alexander Cornelis Arntzenius Hague, Netherlands [21 1 Appl. No. 879,269 [22] Filed Nov. 24, 1969 [45 Patented Oct. 6, 1970 i [73] Assignee Piet C. Blok Delft, Netherlands [54] METHOD AND DEVICE FOR ASSISTING CARDIOVASCULAR CIRCULATION 25 Claims, 8 Drawing Figs.

[52] US. Cl 128/33 1 A6lh 1/00 128 24, 24.2, 33, 50-52 [56] References Cited UNITED STATES PATENTS 2.366,799 l/l945 Luisada l28/24UX Primary ExaminerL. W. Trapp Att0rney-Martin Kirkpatrick ABSTRACT: Equipment for aiding cardiovascular circulation by moving the body synchronously with the pumping action of the heart comprising support means preferably in the form of a table supporting the human body in supine position for reciprocating movement, heartbeat sensing means such as an ECG and power means, preferably hydraulic, responsive to the heartbeat sensing means for moving the support means synchronously with the pumping action of the heart, preferably in a direction generally along the long dimension of the heart and more rapidly in a direction from the aortic valve towards the apex of the heart followed by a slower return.

H51: f? 7554 r SENS/N6 F DE Wall: i I l8 FEEDBACK 1 26 porr/vr/owmr a... HYDRAULIC i PULSE HYDRAULIC 30 FREQUENCY V n i FORM/N6 CONTROL PUWfR DETECTOR I Cum/,7 C/RCU/T srsmw 29 TRIGGER CIRCUIT DELAY CIRCUIT Patented Oct. 6, 1970 3,532,089

Sheet 2 of 5 FIG 3;

VELOCITY f/1EAO L FOOT O/S PLA CEMENT l'l JL 50- 80 M SEC Rl/ PRESSURE MM HG) ECG CORONA/P) FLOW AORT/O FLOW L.l/. PRESSURE (MM HG) Patented Oct. 6, 1970 Sheet mmhstamkmq kuvmmmmk METHOD AND DEVICE FOR ASSISTING CARDIOVASCULAR CIRCULATION This invention relates generally to assisting the function ofa living heart or impaired cardiovascular circulation of a living body. More particularly, it concerns a non-invasive apparatus which is especially useful for assisting heart function.

Most existing devices to assist impaired heart function involve introducing some external mechanism into the body of the patient, which necessitates surgical action, such as introthoracic implantation, or cut-down on a blood vessel, with attendant delay, loss of blood, trauma to the body, and risk of infection, all of which add to the strain on an already darigerously-ill patient. Alternatively, existing devices that operate externally of the body to assist heart function may cause other serious injuries to the patient while attempting to restore circulation.

Accordingly, it is a major object of the present invention to assist the heart function without any surgical intervention, thereby avoiding all such risks.

It is a further object of the invention to provide a device that may be put into operation immediately without any delay required for any surgical procedure.

Still further, it is an object of the invention to provide a device that may be employed for either temporary or prolonged assistance to the patient and that may be operated by relatively untrained personnel.

In order to accomplish these objects, the invention provides apparatus for aiding heart action by reciprocation of the body synchronously with the pumping action of the heart preferably in a direction generally along the vertical or long dimension of the heart to increase the flow of blood from the heart. The in vention comprises support means supporting the body for reciprocationpreferably in a direction generally along said dimension, heartbeat sensing means, and power means responsive to said heartbeat sensing means for reciprocating support means synchronously with the pumping action of the heart. Preferably, said power means reciprocates the support means more rapidly in a direction from the aortic valve towards the apex of the heart followed by a slower return for aiding its pumping action. In another aspect, the invention comprises human body support for such reciprocation.

Still further objects, features and advantages of the invention will appear from the following description of a preferred embodiment thereof, taken together with the accompanying drawings in which:

FIG. 1 shows a diagrammatic view of the apparatus of the invention with a patient on the supporting table thereof, together with a block diagram of the means for reciprocating said table responsive to the heartbeat of a patient thereon;

FIG. 2 is a diagram ofthe left ventricle and aorta of a human heart;

FIG. 3 shows, for a patient being treated by the invention, theelectrocardiogram (ECG) tracing, the body displacement, and the resultant velocity of the body;

FIG. 4 shows, for a patient being treated by the invention, the pressure in the right ventricle, the ECG tracing, coronary flow, aortic flow, left ventricular pressure, and displacement of the body by the apparatus of the invention;

FIGS. 5 and 6 are end and side views of the reciprocating support table element of the invention;

FIG. 7 is a circuit diagram of the electronic control system of the invention; and

FIG. 8 is a circuit diagram of an R-wave detector and artifact rejection circuit, which is utilized when the ECG is employed as an operating signal.

Referring to the drawings and particularly to FIGS. 1 and 2 thereof, the apparatus of the invention uniquely provides means for reducing the work done by the living heart while pumping blood, by accelerating the entire body, during predetermined periods in the cardiac cycle, usually in a direction opposite to that of blood flow from the heart, to assist the ejection of this blood from the left ventricle into the aorta, and similarly to assist ejection of blood from the right ventricle (not shown) into the pulmonary artery (not shown) and enhance venous filling ofthe heart. It may also be used for increasing the work done by the heart, in order to condition the heart, and for maintaining the muscular strength of the 5 heart muscle, for example, during conditions of weightlessness. For this purpose, the acceleration will be in the direction in which blood is ejected into the aorta. v

The energy for the pumping action of the heart is normally supplied by the contraction of the muscle wall of the heart. The acceleration of the body by the apparatus of the invention in a specific direction generally along the vertical or long axis of the heart, at a predetermined time in the cardiac cycle, contributes energy to move blood into the aorta from the heart, consequently reducing the work load on. the heart muscle itself and consequently reducing the energy expended by it.

The apparatus of the invention is unique and different from all other methods presently available for cardiac assistance, including counter pulsation, in that:

I. It utilizes acceleration of the whole body synchronously with the heartbeat.

2.It imparts its external energy to the cardiovascularsystem in systole (contraction) rather than diastole (relaxation).

3. It does not require operative intervention, or intra-vascular manipulation, noranticlottingmeasures.

4. It may be applied with a minimum of effort and time.

In general, as shown in the drawings and particularly FIGS. 1, 5 and 6 thereof, the apparatus of the invention consists of a table 10 supporting the body [f a patient for reciprocation generally along the vertical or long dimension L of the heart 14, a heartbeat sensing device 18 which may be, preferably, an electrocardiographic (ECG) apparatus, or, alternatively a blood pressure transducer, ballistic sensor, or the like, and control and power means including a heartbeat frequency detector 22 and trigger circuit 20, a delay circuit 24, a pulse forming circuit 26, a hydraulic control circuit 28 and a hydraulic power system 29 for reciprocating table 10 preferably more rapidly in a direction from the aortic valve to the apex of the heart followed by a slower return. In treatment, the patient is securely fastened to table 10 for reciprocation therewith in synchronism with his heartbeat as sensed by sensing device 18.

The action of the heart in pumping blood into the aorta normally requires the generation of pressure: by means of the contraction and shortening of muscle fibers in the ventricular wall. This process of producing pressure is oxygen-consuming and is usually impaired in the failing myocardium.

Uniquely, however, by utilization of the apparatus of the invention, energy is added to the circulation and to the heart at that time of ejection when the greatest energy in shortening (systole) occurs, considerably reducing energy expenditure by the heart muscle in achieving ejection, thus enhancing and energizing the normal sequence of ventricular ejection. The R-top of the wave shown in ECG tracing of FIG. 3 precedes the shortening of the heart muscle by 50l00 msec, and the displacement footward of the patient is timed to occur after this delay.

In practice, it has been observed not only that the entire circulation is supported during the use of the apparatus of the invention in such a way that left ventricular pressure, cardiac output and coronary artery bloodflow return to control levels after having been severely depressed (FIG. 4), but also that after support has been continued for some length of time, ventricular ejection and pressure remain more forceful, even after support is discontinued. In other words, the capacity of the heart to contract is not only supported by the temporary application of this device, but even maintains the improvement when the treatment has restored its coronary blood supply. Thus, the device of this invention might also be used toimprove collateral coronary blood flow in situations in which there is a threat of impaired circulation, as, for example, in myocardial infraction. and thereby to minimize the actual damage to the heart muscle.

The novel apparatus of the invention, then, makes possible the generation, transmission and control of external energy imparted to the heart of a patient on table 10. Furthermore, the patient's body can be accelerated rhythmically and synchronously with the heartbeat, with varying degrees of magnitude from to 3g) and duration (0- l()() msec) of acceleration. in addition, modifications to the control mechanism make fractional accelerations during different times of the ejection phase possible, which enhances the efficacy ofthe treatment.

Defining one period of the heartbeat as extending from R- top to R-top, and assuming that the heartbeats on the order of 60 times a minute, in conventional operation to assist impaired circulation, the footward acceleration of the patient will be timed to coincide with the ejection of blood into the aorta, which occurs 50l00 msec after the beginning of a period, or generally after -l0 percent of the period has elapsed. However, in other uses, as to condition a healthy heart by increasing the work load on it, or to maintain muscular strength of a heart under weightless conditions such as might occur in space, the acceleration would be timed to occur for example after less than 5 percent of the period has elapsed, so that the displacement of the patient increases the work that must be done by the heart.

While it will be apparent that the acceleration aforedescribed is imparted to the body with reference to the blood being ejected by the heart, the accelerating force may also be applied by axial rotation of the body as by centrifugation of the supine body. In such case, the heart may be the central axis of rotation but this is unnecessary to impart acceleration of the blood into the ascending aorta. However, such embodiment of the invention is not illustrated herein since it has not been found to have superiority over simple linear acceleration in the long axis of the body. Nevertheless, rotation of the body seated in a chair has been found to be effective. In this latter situation, the rotational force is accom' plished by rapidly rotating the seated human in a frontal direction. This type of rotation is accomplished by placing a torque on the seated patient, the centrifugal force accelerating the blood from the heart. The central axis of rotation need not be the heart. The accelerating force is stronger when the axis of rotation is at a point further distant to the heart. An advantage to using the heart as the axis of rotation is established by the fact the heart is the central point of acceleration and that the fluid in the descending aorta is also accelerated away from the heart which is not accomplished by linear acceleration. Since the main object is to empty the heart into elastic blood vessels, the primary object of the force is to assist the ventricles and thiscan be accomplished best if the heart is not made the axis of rotation. The rotational speeds required when the heart is the center are high, and this places undue stress on vessels distant to the heart. The rotation of the sitting patient is especially suitable for cardiac patients who may be orthopneic and uncomfortable in the reclining position. They can be rocked in a to and fro manner using the chair like the weight on the pendulum of a metronome, each swing being synchronous with the heart rate. This means of acceleration has some advantage over a linear accelerating force in that it may be applied for a longer duration. Rotational acceleration is best accomplished with the patient in the sitting position but it is also possible to linearly accelerate supine patients.

It will also be apparent that the aforedescribed apparatus does not take advantage of the gravitational force which is constantly influencing the body except for weightless conditions in space. if acceleration and deceleration is accomplished at a right angle to the gravitational field, the patient need not be accelerated to the same extent as in the reclining position done horizontal to the earths gravitational field. In this case, the sitting patient is accelerated toward the earth synchronously with the heart beat and slowly raised in position in the chair during diastole. While this embodiment of the invention may be most satisfactory for some cardiac patients, it is not satisfactory for sick patients who must remain recumbent, Therefore, a detailed description of the embodiment of the invention will be restricted to linear acceleration ofthe supine patient merely mentioning that angular rotation should supply the same force as linear acceleration. 5 By established practice, the patient is placed in a bed. Therefore, the invention will describe the patient on a plain supporting surface, though it will be apparent that the patient might be supported in a fluid medium and made to move with a fluid system, for example.

Finally, while the preferred embodiment of the invention describes an accelerating force, it will be apparent that deceleration could be also employed, since such will also ac complish the desired change in the rate of motion ofthe body.

More specifically, and referring now to FIG. 1, the patient is supported on a linear acceleration table 10, whose top is made of an X-ray transparent material such as wood or lucite, permitting the recording of video images or cine angiocardiograms, ifnecessary.

The patient is attached to table by means of a matress which, according to another aspect of the invention, comprises a bag of flexible sheet material 11, containing, for example, a rigid foam polystyrene plastic. This material, in fluid form capable of setting to provide a rigid mass 13, is injected into the bag immediately before the patient is placed on it. The flexible surface of the bag then takes on acontour conforming to the body contours of the patient and within minutes the material sets, becoming a hardened, rigid, nonrcsilient material providing a rigid, contoured underlying supporting surface. The chest is left free so that the patient can breathe. The patient is then securely fastened to the table top and the support so provided by means of suitable straps 16.

Referring to FIGS. 5 and 6, the table 10 is fastened to a heavy steel base 30 and supported by six flat springs 31. Alternatively, it may be supported by guide ways or ball bushings on cylindrical bars, or an air cushion, which latter would have the advantage of permitting simultaneous ballistocardiography. Hydraulic servomotor 34 for reciprocating table 10 is positioned immediately underneath the table top; it is supported on base 30 and is connected to its operating servo valve 32. A table displacement potentiometer 33 is also mounted on base 30 with its movable element connected to table 10.

Table 10 is actuated in response to signals representing the natural function of the patient's heart. The significant information is the strength and duration of the contraction of the heart muscle and the frequency with which the contraction occurs. This inherent activity of the heart may be measured in one or more ways. An electrocardiographic (ECG) signal can be obtained from electrodes attached to the body; or a pressure signal (or its first derivative, the rate of change in pressure) can be recorded from high fidelity pressure transducers inside the great vessels of the ventricle. Thirdly, an acceleration transducer can be attached to the body. Finally, an ultra low frequency ballistocardiogram can be obtained. The choice of signal will in practice depend on the urgency of the situation. An electrocardiographic signal can be obtained within minutes, whereas a pressure signal requires the insertion of the transducer on a catheter. On the other hand, direct utilization of the pressure would have the advantage of synchronizing the functioning of the apparatus with the pressure as it is being developed by the myocardium.

in the specific embodiment described herein, the signal may be obtained from an electrocardiograph, which processes an electrical potential developed by the heart muscle during the cycle of the heartbeat. FIG. 8, which will hereinafter be explained, shows in detail circuitry to process such an electrical heart signal for use by the control system of the invention, while rejecting signals from the patient that will not be followed by a contraction of the heart muscle.

Whatever means is selected to represent the heart function, signals from heartbeat sensing device 18 are used to control the hydraulic control circuit 28 and hydraulic power system 29 and thus determine the motion oftable l0.

Referring back to FIG. 1, as well as to FIG. 7, trigger circuit 20 receives the amplified signals from heartbeat sensor 18. Since in normal sinus rhythm, the heartbeat frequency may change the signal from sensing device 18 goes additionally to frequency detector 22, from which information on the frequency of the patients natural heart function is derived to adjust the settings of delay circuit 24 and pulse forming unit 26. The length of the delay time or the width of the pulse supplied from pulse-forming unit 26 may then be altered automatically to reflect changes in the heartbeat interval. These circuits may additionally be and preferably are manually adjustable by suitable means during operation. Trigger circuit 20 derives from the amplified signal a trigger pulse, which is input to delay circuit 24, and then is input, with the delay, to pulseforming unit 26.

Pulse forming circuit 26 forms a pulse which is then fed to hydraulic control circuit 28, which sends a driving pulse to the two-stage electro-hydraulic servovalve 32, which in turn controls the operation of a piston cylinder hydraulic servomotor 34 which drives table 10. The amplitude of the driving pulse can be utilized to control the magnitude of acceleration, and its width may be applied in controlling the duration. Servomotor 34 drives the table with an acceleration corresponding in polarity, magnitude and duration to the pulse from control circuit 28.

The pulses from pulse forming circuit 26 are fed into a first order element 50. Since the time constant of this first order element is about one second and the pulses are only maximum for about 100 msec, the output signal contains some steep flanks of which the slope is proportional to the height of the corresponding input pulse. The output signal of first order element 50 passes through on-off switch 52; the magnitude of the voltage may be varied by control potentiometer 53, from which the pulse goes through the unit gain inverter voltage amplifier 54 to a potentiometer 56.

To prevent damaging of servomotor 34 due to an excessive displacement of table produced by an abnormally irregular repetition rate of the pulse train, a centering unit 70 is included in the control system. A voltage from displacement potentiometer 33 at table 10, passed through a gain-adjusting potentiometer 62, provides a location feedback signal. When the voltage from the feed-back potentiometer 33 equals either of the constant voltages +V, V, indicating that table 10 has reached a maximum displacement in either direction, one of the comparators 72 generates a pulse which trips a relay, and the position feed-back signal is fed directly to integrator 64, with a factor of 10 amplification. The direction of the displacement is indicated by the voltage onpotentiometer 62. In tegrator 64 then vary rapidly generates an output signal that forces table 10 back into the mid-position. The relay remains closed until table 10 returns to mid-position.

FIG. 8 shows an Rwave detector and artifact rejection circuit which may be used with heartbeat sensing device 18 to provide improved input signals to trigger circuit and frequency detector 22. This circuit generates a pulse which initiates each cycleof table 10 at a predetermined point on each Q to R segment on the patients electrocardiogram (FIG. 3). The circuit includes provisions to minimize the chances of missing a QRS complex because of baseline drifts or amplitude variations. The system also rejects the artifacts which are generated by the table acceleration or by other muscles of the patient's body.

As shown in FIG. 8, the amplified ECG signal passes from the preamplifier 80 through a dual band pass filter 81 to the input of electronic switch 82. Band pass filter 81 rejects low frequency and high frequency components which are not necessary to the detecting of the QRS complex. The filtered ECG signal passes through electronic switch 82 and one shot multivibrator 83 to an amplitude peak detector 84 whose output is a measure of the most recent QRS peak amplitude. A manually adjusted comparator potentiometer 85 permits selection of some fraction of this stored peak amplitude as a marking level for the next QRS complex.

When the instantaneous amplitude of the QRS complex just equals the fraction of the previous peak amplitude, a driving pulse is applied both to the control logic of table 10 and to a delay system in the R detector consisting of a further elec tronic switch 86 and amplitude peak detector 87 connected to multivibrator 83. Peak detector 87 is also provided with a comparator potentiometer 88. The signal through the delay circuit thus blocks the one shot multivibrator 83 for a suitable time period. The ECG signal is hence removed from the peak detector during such delay, assuring that only the R amplitude will be stored. The delay is dynamically adjusted to the average of a recent sequence of R to R intervals so that the artifact rejection characteristics of the circuit may follow minor variations in heart rate. However, the use of the circuit of FIG. 8, though desirable, is not essential to the invention.

When the apparatus of the invention is used in treating a patient, signals, preferably from an electrocardiograph (ECG) representing the inherent function of the patients heart are transmitted by sensor 18, with or without the circuitry of FIG. 8 to trigger circuit 20, which derives therefrom a trigger pulse to initiate the control process to accelerate the patient. Since the electrical cycle of the heartbeat is somewhat in advance of the muscular action of the heart, and since the frequency of the heartbeats may vary with time, a delay determined by the characteristics of the natural heart function is added in circuit 24 to insure that the acceleration of the patient by the table occurs at the time when the heart pumps blood into the aorta.

Pulse forming circuit 24 generates a control pulse in response to the delayed trigger pulse and to the frequency as sensed by detector 22, and hydraulic control circuit 28 actuates hydraulic power system 29 to accelerate table 10. As the patient's heart ejects blood into the aorta, table 10 simultaneously accelerates the patient along line L (FIGS. 1 and 2) in the direction opposite to the flow of blood, that is, towards the patients feet. The magnitude and duration of this acceleration correspond to the characteristics of the control pulse and thus ultimately to the signal representing the patient's natural heart function. After the patient has been thus rapidly moved footwards, table 10 returns more slowly to its initial position during the period when the patients heart is again filling with blood. Since the patients body and blood vessels, including the aorta, are accelerated in a direction opposite to the flow of the blood ejected by the heart, the work that must be done by the heart muscle to accelerate the blood out of the heart is correspondingly reduced, and the energy and oxygen demands on the heart are lowered while circulation of the blood is assisted.

Enhanced circulation produces improved oxygen supply to the heart as well as to the rest of the body, and the heart function improves correspondingly. The apparatus is continued in use as long as necessary.

As has earlier been pointed out, the apparatus of the invention may be used for other purposes than assisting impaired cardiovascular circulation, for example, for conditioning the heart as is desirable during conditions of weightlessness, or to improve collateral coronary blood flow in situations in which there is a threat of impaired circulation.

Still further aspects and variations of the invention, within the spirit thereof and the scope of the appended claims, will be apparent to those skilled in the art.

I claim:

1. Apparatus for aiding cardiovascular circulation by moving the body synchronously with the pumping action of the heart comprising:

support means supporting the body for movement;

heartbeat sensing means; and

power means responsive to said heartbeat sensing means for moving said support means synchronously with the pumping action ofthe heart.

2. Apparatus as claimed in claim 1 including means wherein the initiation of movement of said support means by said power means is delayed with respect to the sensed signal of an individual heartbeat.

3. Apparatus as claimed in claim 1 wherein the power means moves said support means in a direction generally along the long dimension of the heart.

4. Apparatus as claimed in claim 3 wherein said power means moves said support means more rapidly in a direction from the aortic valve towards the apex of the heart than in the return direction.

5. Apparatus as claimed in claim 1 wherein said power means is hydraulically operated.

6. Apparatus for aiding cardiovascular circulation by moving the body synchronously with the pumping action of the heart comprising:

support means supporting the body for movement;

heartbeat sensing means sensing both the signal and amplitude of the individual heartbeats; and

power means responsive to the time and amplitude of individual heartbeats for moving said support means. 7. Apparatus as claimed in claim 6 wherein said power means moves said support means more rapidly in a direction from the aortic valve towards the apex of the heart as an inverse function of heartbeat amplitude.

8. Apparatus for aiding cardiovascular circulation by reciprocation of the body synchronously with the pumping action of the heart comprising:

support means supporting the body for reciprocation; heartbeat sensing means sensing both the signal of the individual heartbeats and the heartbeat frequency; and

power means responsive to both the individual heartbeats and to the frequency thereof for reciprocating said support means synchronously with the pumping action of the heart.

9. Apparatus as claimed in claim 8 including means wherein the initiation of reciprocation of said support means by said power means is delayed with respect to the sensed signal of an individual heartbeat by a delay time which is a function of the heartbeat frequency.

10. Apparatus as claimed in claim 8 wherein:

said heartbeat sensing means further including means for sensing the amplitude of the heartbeat; and said power means is responsive to said amplitude. 11. Apparatus for aiding cardiovascular circulation by reciprocation of the body synchronously with the pumping action of the heart comprising:

support means supporting the body for reciprocation in a direction generally along the long dimension of the heart;

heartbeat sensing means including an ECG sensing the signal of each individual heartbeat, its amplitude and the heartbeat frequency; and

power means responsive to said heartbeat sensing means for moving said support means synchronously with the pumping action of the heart, the initiation of reciprocation of said support means by said power means being delayed with respect to the sensed signal of an individual heartbeat by a delay time which is a function of the heartbeat frequency, said power means moving said support means more rapidly in a direction from the aortic valve towards the apex of the heart than in the reverse as an inverse function of heartbeat amplitude.

12. Apparatus for aiding cardiovascular circulation by reciprocating the body synchronously with the pumping action of the heart comprising:

support means supporting the body for reciprocation;

heartbeat sensing means providing an individual heartbeat signal; and

hydraulic power means for reciprocating said support means more rapidly in a direction from the aortic valve towards the apex of the heart than in the return direction, said power means being responsive to said heartbeat signal to initiate movement of said support means in said direction at a predetermined point in the heartbeat cycle. 13. Apparatus as claimed in claim 12 wherein: said heartbeat sensing means further includes heartbeat frequency detecting means to detect the frequency of the natural heartbeat; I said power means further includes triggering means responsive to said sensing means to form a trigger pulse;

delay means responsive to said detecting means and to said triggering means to impart an appropriate delay to said trigger pulse; and

pulse-forming means responsive to said delay means, to said triggering means and to said detecting means, to form pulses for controlling the reciprocation of said power means.

14. The apparatus of claim 13 wherein said hydraulic power means includes a hydraulic servomotor for actuating said support means, controlled by a hydraulic valve responsive to said pulse-forming means.

15. Method for aiding cardiovascular circulation by moving the body synchronously with the pumping action of the heart comprising:

sensing the heart beat; and

moving said body synchronously with the sensed heartbeat to aid pumping action of the heart.

16. Method as claimed in claim 15 wherein the initiation of movement is delayed with respect to the sensed signal of an individual heartbeat.

17. Method as claimed in claim 15 wherein said movement is in a direction generally along the long dimension of the heart.

18. Method as claimed in claim 17 wherein said movement is more rapid in a direction from the aortic valve towards the apex of the heart than in the return direction.

19. Method as claimed in claim 15 wherein both the signal and amplitude of the individual heartbeats are sensed and said movement is responsive to the signal and amplitude of individual heartbeats.

20. Method as claimed in claim 19 wherein said movement is more rapid in a direction from the aortic valve towards the apex of the heart as an inverse function of heartbeat amplitude.

21. Method for aiding cardiovascular circulation by recipro cation of the body synchronously with the pumping action of the heart comprising:

sensing both the signal of the individual heartbeats and the heartbeat frequency; and

reciprocating the body synchronously with the pumping action of the heart responsive to both the individual heartbeat signals and to the frequency thereof.

22. Method as claimed in claim 21 wherein the initiation of reciprocation is delayed with respect to the sensed time of an individual heartbeat by a delay signal which is a function of the heartbeat frequency.

23. Method as claimed in claim 21 wherein the amplitude of the heartbeat is sensed and the movement is responsive to said amplitude.

24. Apparatus for aiding cardiovascular circulation by moving a body synchronously with the pumping action of the heart, comprising:

support means to support the body for movement therewith;

sensing means to detect a parameter of the body heartbeat;

a motor operatively connected to said support means to accelerate said support means in at least a first direction; and

said motor being operatively connected to said sensing means and responsive to said parameter to effect said acceleration with respect thereto.

25. Apparatus for aiding cardiovascular circulation according to claim 24 said parameters including heartbeat occurrence signal, heartbeat frequency, and heartbeat amplitude, and said apparatus further comprises circuit means to provide a motor signal to said motor at a definite time relative to said heartbeat occurrence signal and to modulate said motor signal as a function of said heartbeat frequency and amplitude. 

